JP2553053B2 - Optoelectronic scanning head - Google Patents

Abstract

An opto-electronic scanning head for drum and flat bed scanning apparatus for point-by-point and line-by-line scanning of opaque and transparent originals which are illuminated point-by-point. The housing of the scanning head 7 has a front panel 9 which is displaceable along the optical axis 12 of the scanning objective lens 11 and has a housing part which is stationary with respect to the optical axis 12. The scanning objective 11 is mounted in the front panel 9, but the diaphragm 13 and the opto-electronic transducer 14 are mounted in the housing portion 8. The scanning objective 11 can be displaced over a broad range with a sensitive adjustment mechanism for the front panel 9 so that the focus range can always be placed into the image plane of the originals and thus optimum image sharpness can be achieved for originals having all different thicknesses. In the scanning head 7 for opaque scanning, the illumination system 27, 28, 29, and 31 is used for the point to point illumination of the originals and the illumination system is arranged in the displaceable front panel 9 such that the optical axis 30 extends through the focus range of the scanning objective 11 and as a result the illumination system 27, 28 and 29 always generates a focus illumination point on the original regardless of the position of the front panel 9 or of the scanning objective 11 so that optimum illumination of the originals is always achieved for all thicknesses of originals and also the optimum image is maintained sharp.

Description

Description: FIELD OF THE INVENTION This invention relates to the field of electronic reproduction technology and more particularly to optoelectronics for drum or flatbed scanning devices for dot and line scanning of reflective and transmissive originals. The expression scan head.

2. Description of the Related Art In a drum type scanning apparatus, a document to be reproduced is spread on a scanning drum as a document carrier and is scanned by an optoelectronic scanning head that moves axially along a rotating scanning drum. The line is scanned. The scanning head mainly comprises a scanning objective, an aperture and an optoelectronic transducer.
The original is spot-wise exposed. The scanning light, which is modulated by the information content of the original document and which originates from the exposure spots on the original document, passes through the scanning objective lens and the diaphragm and reaches the optoelectronic converter. The converter converts the scanning light into an electrical image signal. When scanning a transparent original, the exposure mechanism is located inside a scanning drum made of a transparent material, and the scanning light transmitted through the transparent original reaches the scanning head. In this type, the exposure system and the scanning head scan. It can be moved synchronously in the axial direction of the drum. In scanning a reflective original, the exposure mechanism is a component of the scanning head, and the scanning light reflected from the reflective original is evaluated within the scanning head. In a flatbed scanner, the document carrier is a flat surface.

In order to scan the document with the optimum sharpness of the image, the focal range of the scanning objective lens must be located in the image plane of the document, or the distance between the image plane and the scanning objective lens is always Must be constant. However, because documents of different thickness must be scanned and the diameter of the scanning drum used has scanning errors, the sharpness of the image must be often controlled and possibly corrected. With conventional scanning heads, the correction of image sharpness is possible only in a limited range, since the scanning objective can only move along the optical axis within a narrow range,
This range is not sufficient to achieve optimum adjustment of image sharpness and thus good scanning quality for all document thicknesses placed. In order to eliminate these drawbacks, different scanning drums have been produced with radius differences corresponding to the frequently used document thickness. By this means the distance between the image plane and the scanning objective can be kept almost constant, but it is very expensive.

When assembling a conventional scanning head for scanning a reflective original, the exposure mechanism integrated in the scanning head is adjusted once and fixed so that the exposure spot is sharply imaged with respect to the set position of the scanning objective. To be done. However, the sharp imaging of this exposure spot is lost when the scanning objective is moved from the set position to adjust the sharpness of the image. Another drawback of conventional scanning heads is that proper post-adjustment of the exposure mechanism is often not possible at all, or difficult for untrained operators and can only be carried out over a large amount of time. is there.

Problems to be Solved by the Invention An object of the present invention is to provide a transparent original and a reflective original in which optimum adjustment of the image sharpness and the exposure spot can be carried out quickly, delicately and precisely with respect to a wide range of original thicknesses. An optoelectronic scanning head for a scanning device for scanning.

Means for Solving the Problems The means of the present invention for solving the above problems is an optoelectronic scanning head for performing dot scanning and line scanning of a document placed on a document carrier. A mechanism is provided, wherein the scanning mechanism includes a scanning objective lens, a diaphragm arranged along the optical axis of the scanning objective lens, and at least one optical unit arranged along the optical axis of the scanning objective lens. An electronic converter is provided, and a casing part movable along the optical axis is provided facing the original carrier side, and a scanning objective lens is arranged inside the casing part. A casing part which is connected to this casing part and which is immovable with respect to the optical axis is provided on the side opposite to the document carrier. In a scanning head in which an aperture and an optoelectronic transducer are arranged, two guide bars extending parallel to each other along the optical axis for changing the distance from the scanning objective lens to the surface of the document carrier. Is fixed to the movable casing part and projects into the stationary casing part, for guiding the other of the guide rod and the slide bearing mechanism for slidingly supporting one of the guide rods without play. The rolling bearing mechanism and the rolling bearing mechanism are arranged in a stationary casing part, a rack extending along the optical axis direction is fixed to one guide rod guided in the sliding bearing mechanism, and a rotatable pinion is provided. The pinion is provided perpendicularly to the optical axis, the pinion meshes with the rack, and a rotatably supported shaft is provided in a stationary casing part. The pinion is fixed to one end of the shaft, and the knob is fixed to the other end of the shaft. The rotation of the knob changes the distance from the scanning objective lens to the surface of the document carrier. That is.

With respect to the scanning head for scanning the reflection original, the above-mentioned problems can be solved by the features described in claims 1 to 3.

With the optoelectronic scanning head constructed according to the invention, optimum adjustment of the image sharpness and exposure spot can be carried out quickly, delicately and precisely for a wide range of document thicknesses.

Embodiment FIG. 1a shows a sectional view of an apparatus for scanning a transparent original. The document carrier is a scanning drum 1 made of transparent material, which rotates in the direction indicated by the arrow 3 about an axis 2 extending in a direction perpendicular to the drawing plane. Transparent original 4 to be scanned on the scanning drum 1
Has been fixed. Provided inside the scanning drum 1,
The movable exposure mechanism 5, which is not shown in detail, is the transparent original 4.
An exposure spot is formed in the image plane of (1), and the transmission document 4 is exposed in a dot type and a line type based on the movement of the exposure mechanism 5 in the direction of the axis 2 and the rotation of the scanning drum 1. The scanning head 7 of the drum scanner is mainly a casing part 8 which is open in the direction of the scanning drum 1.
And a front plate 9 which is a casing portion facing the scanning drum 1. The front plate 9 of the scanning head 7 has a hole 10 in which a scanning objective 11 is arranged and is fixedly connected to the front plate 9. The optical axis 12 of the scanning objective lens 11 extends in the radial direction of the scanning drum 1. An image point diaphragm 13 and an optoelectronic converter 14 are arranged in the exposure path along the optical axis 12 of the scanning objective lens 11 of the casing part 8 of the scanning head 7 and are arranged in a suitable manner in the casing. It is fixed to the part 8.

The scanning light beam 15 which starts from the exposure spot 6 on the transparent original 4 and which is modulated by the information content of the transparent original 4 is projected by the scanning objective lens 11 onto the image point diaphragm 13. Image point diaphragm 13
Is a scanning light beam 15 which is an optoelectronic converter in which only the scanning light beam starting from the original image point in the exposure spot 6 is used.
Enter 14 and limit here to being converted to an electrical image signal on conductor 16.

The front plate 9 of the scanning head 7 comprises a casing part 8 together with the scanning objective lens 11.
With respect to it, it is connected to the casing part 8 by means of a feed mechanism (not shown in FIG. 1a) such that it can be moved in the direction of the optical axis 12 within a large range. This allows the focus range of the scanning objective 11 to be moved into the image plane of the original being scanned at that moment, thereby providing optimum image sharpness for all emerging document thicknesses. Thus, high scanning quality is achieved.

A moving nut 17 is mounted on the bottom of the casing part 8 and engages a lead screw spindle 18 which is aligned parallel to the axis 2 of the scanning drum 1. Due to the rotation of the feed screw spindle 18, the casing part 8 of the scanning head 7 keeps a certain distance unique to the apparatus, and the front plate 9 or the scanning objective lens.
11 is allowed to pass through the peripheral surface of the scanning drum 1 in the axial direction while keeping the distance adjusted each time.

The swivel mirror 19 shown by a broken line swivels to move the scanning objective lens 11
The scanning mirror 15 can be located in a scanning light beam 15 starting from a swivel mirror 19 which reflects the scanning light beam 15 in the casing part 8 in the direction of an eyepiece 20 with a glass 22 serving as a loupe 21. This causes a magnified image of the image point being scanned at that moment and the environment immediately surrounding it to appear on the frosted glass 22, which makes it much easier to adjust the image sharpness.

In most drum-type scanning devices, the scanning head 7 is located behind the scanning drum 1 when viewed from the operating side of the device, so at that moment, the original portion grasped by the scanning head 7 is observed on the back surface of the scanning drum 1. It is often difficult for the operator to adjust the scanning head 7 to a characteristic document point for the purpose of machine calibration. For this reason, a mirror 23 is mounted above the scanning objective lens 11 of the front plate 9 so that the operator can observe and judge the image point environment on the transparent original 4 at each time. it can.

A cover hood 24 is further attached to the front plate 9, and the cover hood 24 grips the open side of the casing part 8 from the outside to protect the inner chamber of the casing part 8 from the incidence of outside light.

FIG. 1b is a sectional view of an apparatus for scanning a reflection original, which is different from the sectional view shown in FIG. 1a in that the exposure mechanism is not provided inside the scanning drum 1 and the scanning head 7 is configured. It is different in that it is a member. The front plate 9 additionally has a conical notch 27 symmetrically positioned with respect to the optical axis 12 of the scanning objective 11. The side wall of the cutout 27 is provided with a large number of holes 28 distributed around the scanning objective 11, only two of which are visible in the drawing. An exposure optical mechanism of the exposure mechanism or a condenser 29 is arranged in the hole 28, and the optical axis 30 of the exposure optical mechanism is set once when the scanning head 7 is assembled.
Aligned to extend through 11 focal areas.
An exposure light beam generated from a light source (not shown) of the exposure mechanism is conveyed to each condenser 29 via a light guide cable 31, and by the condenser 29, a sharp exposure spot 6 in a focal plane 32 of the scanning objective lens 11. Is superimposed on. Optical axis 12
Nos. 30 and 30 always "see" the sharp exposure spot 6 regardless of the position of the front plate 9 when the front plate 9 moves. The focal plane of the scanning objective 11 is then moved into the image plane of the reflecting original being scanned at that moment, so that in an advantageous manner an optimum exposure of the original and an optimum image sharpness are achieved.

The invention is not limited to the embodiments described. The scanning heads can also be used in flatbed scanning devices. In this case, the original carrier is a flat surface, and this surface moves relative to the scanning head. The scanning head comprises a photodiode array or a photodiode matrix instead of a separate optoelectronic converter for converting the scanning light. The exposure mechanism described in the scanning head for scanning the reflection original can be modified to each shape. Of course, the scanning head according to the invention may also be equipped with additional devices for applying an electronic blur mask and / or for scanning color documents.

FIG. 2 shows a perspective view of the scanning drum 1 and the scanning head 7 for scanning the reflection original. The structural configuration of the above-mentioned feeding mechanism provided between the stationary casing portion 8 and the movable front casing 9 will be described with reference to FIG. A reflection original 4 to be scanned is arranged on the scanning drum 1. On the front surface of the front plate 9, the scanning objective lens 11, the conical notch 27, and the condenser 29 and the mirror 23 of the exposure mechanism grouped around the scanning objective lens 11 can be seen. The casing part 8 is provided with a moving nut 17, which is a lead screw spindle for moving the scanning head 7 axially along the scanning drum 1 in the direction indicated by the arrow 33.
It meshes with 18. Two guide rods 34 and 35, which are perpendicular to the front plate 9 and parallel to each other, are fixed to the front plate 9. The guide rods 34, 35 project into the housing part 8 and here the distance between the front plate 9 and the scanning objective 1 1 to the scanning drum 1 is adjustable in the radial direction indicated by the arrow 36. Is movably guided and supported. A part of the casing wall is designed as a guide groove 37 for the guide rod 34 in the radial direction of the scanning drum 1 and is coated with a suitable sliding material. The guide rod 34 has two springs 38 and 39.
It is mounted so that it slides in the guide groove 37 and is free of play. Another guide rod 35 moves between two rolling bearing mechanisms 40, 41 fixed to the casing part 8. The guide rod 34 moves as a driving member for moving the front plate 9. Guide groove 37 for that
The guide rod 34 within the range has a rectangular notch 42 extending in the longitudinal direction on the surface. A rack 43 is formed in this notch 42, and the length of the rack 43 determines the maximum possible movement distance of the front plate 9. A pinion 44, which is vertically aligned with the feeding device, engages with the rack 43, and the pinion 44 is connected to a knob 46 via a shaft 45 supported in the casing part 8. Rotation of the knob 46 or the pinion 44 causes the rack 43 to make a corresponding linear movement in the direction indicated by the arrow 36, which movement is transmitted to the front plate 9 via the guide rod 34. Subtle movement adjustments are possible in an advantageous way by choosing the appropriate leads for the rack 43 and pinion 44.

[Brief description of drawings]

FIGS. 1a and 1b are partial cross-sectional views of a scanning drum of a drum type scanning device, which are not shown in detail for explaining the principle of the present invention, showing the scanning drum in a radial direction and the scanning head on the optical axis. The corresponding cross-section taken along section, FIG. 2, is a perspective view of the scanning head. 1 ... scanning drum, 2 ... axis, 3 ... arrow, 4 ... original, 5 ... exposure mechanism, 6 ... exposure spot, 7 ... scan head, 8 ... casing part, 9 ... front plate , 10 ... hole, 11 ... scanning objective lens, 12 ... axis, 13
…… Image point diaphragm, 14 …… Converter, 15 …… Scanning light flux, 16 ……
Conductor wire, 17 …… moving nut, 18 …… feed screw spindle,
19 …… Swivel mirror, 20 …… Eyepiece, 21 …… Loupe, 22 …… Glass, 23 …… Mirror, 24 …… Cover hood, 27 …… Notch, 28 …… Hole, 29 …… Condenser, 30 …… Axis, 31 ……
Light guide cable, 32 ... focal plane, 33, 36 ... arrow, 34, 35 ...
… Guide rod, 37 …… Guide groove, 38, 39 …… Spring, 40, 41
...... Rolling bearing mechanism, 42 ...... Notch, 43 ...... Luck,
44 …… pinion, 45 …… axis, 46 …… knob.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ulritzhi Pearl Reisdorf Play Tour Germany Schutlerse 51 (72) Inventor Rututz Rebetge Kiel 14, Germany Yugern Berger Schutlerse 73a (56) Reference References JP 57-173257 (JP, A) JP 55-137767 (JP, A) JP 60-187174 (JP, A) Actual development 60-95764 (JP, U) Actual development 55- 61371 (JP, U)

Claims (4)

(57) [Claims] 1. An optoelectronic scanning head for dot scanning and line scanning of a document placed on a document carrier, comprising a scanning mechanism, said scanning mechanism comprising a scanning objective lens (11). And an aperture stop (1) arranged along the optical axis (12) of the scanning objective lens (11).
3) and at least one optoelectronic converter (14) arranged along the optical axis (12) of the scanning objective lens (11), and along the optical axis (12) A movable casing part (9) is provided facing the original carrier (1) side, and a scanning objective lens (1) is provided.
1) is arranged inside this casing part and is connected to this casing part, and a casing part (8) immovable with respect to the optical axis (12) is provided on the side opposite to the document carrier (1). In the scanning head, in which the diaphragm (13) and the optoelectronic converter are arranged inside the stationary casing part, the distance from the scanning objective lens (11) to the surface of the document carrier (1) is set. Two guide rods (34; 35) extending parallel to each other along the direction of the optical axis (12) for changing are fixed to a movable casing part (9) and are immovable. ), And a slide bearing mechanism (37; 3 for slidingly supporting one of the guide rods (34) without play.
8; 39) and the rolling bearing mechanism (40; 41) for guiding the other of the guide rods (35) are immovable casing parts (8)
A rack (43), which is arranged inside and extends in the direction of the optical axis (12), is fixed to one guide rod (34) guided in the slide bearing mechanism (37; 38; 39). , A rotatable pinion (44) is provided perpendicular to the optical axis (12), and the pinion meshes with the rack (43),
A shaft (45) rotatably supported is provided in the stationary casing part (8), and the pinion (44) is fixed to one end of the shaft and the knob (46) is fixed to the other end. The optoelectronic scanning head is characterized in that the distance from the scanning objective lens (11) to the surface of the document carrier (1) is changed by rotating the knob (46). 2. A slide bearing mechanism (37; 38; 39) is provided in the stationary casing part (8) and is lined with a slide sheet and one of the guide groove (37) is provided. Leaf spring (38; 3) for holding the guide rod (34) of
9) A scanning head according to claim 1, which is composed of 3. At least one light source (29) is fixed to a casing part (9) movable for scanning a reflective document, the optical axis (30) of the light source (29) and a scanning objective lens (9). The intersection with the optical axis (12) of 11) is the scanning objective lens (11)
The scanning head according to claim 1 or 2, wherein the light source (29) is adjusted in position with respect to the scanning objective lens (11) so as to be located in the focal plane. 4. A mirror (23) is mounted above the scanning objective lens (11) on the surface of the movable casing part (9) facing the document carrier (1) side. The scanning head according to any one of items 1 to 3.